Nikon D3100 vs Sony A5100

The Nikon D3100 and the Sony Alpha A5100 are two digital cameras that were officially introduced, respectively, in August 2010 and August 2014. The D3100 is a DSLR, while the A5100 is a mirrorless interchangeable lens camera. Both cameras are equipped with an APS-C sensor. The Nikon has a resolution of 14.2 megapixels, whereas the Sony provides 24 MP.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Nikon D3100		Sony A5100
Digital single lens reflex		Mirrorless system camera
Nikon F mount lenses		Sony E mount lenses
14.2 MP – APS-C sensor		24 MP – APS-C sensor
1080/24p Video		1080/60p Video
ISO 100-3,200 (100 - 12,800)		ISO 100-25,600
Optical viewfinder		No viewfinder, LCD framing
3.0" LCD – 230k dots		3.0" LCD – 922k dots
Fixed screen (not touch-sensitive)		Tilting touchscreen
3 shutter flaps per second		6 shutter flaps per second
550 shots per battery charge		400 shots per battery charge
124 x 96 x 75 mm, 505 g		110 x 63 x 36 mm, 283 g

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Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D3100 and the Sony Alpha A5100? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.

Body comparison

The side-by-side display below illustrates the physical size and weight of the Nikon D3100 and the Sony A5100. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All size dimensions are rounded to the nearest millimeter.

The D3100 can be obtained in two different colors (black, red), while the A5100 is also available in two color-versions, but different ones (black, white).

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A5100 is considerably smaller (42 percent) than the Nikon D3100. Moreover, the A5100 is substantially lighter (44 percent) than the D3100. In this context, it is worth noting that neither the D3100 nor the A5100 are weather-sealed.

The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. Both cameras have similarly sized sensors, but DSLRs have a larger flange-to-focal plane distance than mirrorless cameras, which imposes contraints on the optical engineering process and generally leads to bigger and heavier lenses. You can compare the optics available for the two cameras in the Nikon Lens Catalog (D3100) and the Sony E-Mount Lens Catalog (A5100). Mirrorless cameras, such as the A5100, have moreover the advantage that they can use many lenses from other systems via adapters, as they have a relatively short flange to focal plane distance.

Concerning battery life, the D3100 gets 550 shots out of its Nikon EN-EL14 battery, while the A5100 can take 400 images on a single charge of its Sony NP-FW50 power pack. The power pack in the A5100 can be charged via the USB port, which can be very convenient when travelling.

The table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D3100	124 mm	96 mm	75 mm	505 g	550	n	Aug 2010	599	ebay.com
2.		Sony A5100	110 mm	63 mm	36 mm	283 g	400	n	Aug 2014	549	ebay.com
3.		Nikon D40	124 mm	94 mm	64 mm	522 g	470	n	Nov 2006	499	ebay.com
4.		Nikon D40X	124 mm	94 mm	64 mm	522 g	520	n	Mar 2007	729	ebay.com
5.		Nikon D60	126 mm	94 mm	64 mm	522 g	500	n	Jan 2008	629	ebay.com
6.		Nikon D3000	126 mm	97 mm	64 mm	536 g	500	n	Jul 2009	599	ebay.com
7.		Nikon D3200	125 mm	96 mm	77 mm	505 g	540	n	Apr 2012	599	ebay.com
8.		Nikon D5000	127 mm	104 mm	80 mm	590 g	510	n	Apr 2009	749	ebay.com
9.		Nikon D5100	128 mm	97 mm	79 mm	560 g	660	n	Apr 2011	749	ebay.com
10.		Nikon D7000	132 mm	105 mm	77 mm	780 g	1050	Y	Sep 2010	1,499	ebay.com
11.		Sony A3000	128 mm	91 mm	85 mm	411 g	470	n	Aug 2013	329	ebay.com
12.		Sony A5000	110 mm	63 mm	36 mm	269 g	420	n	Jan 2014	449	ebay.com
13.		Sony A6000	120 mm	67 mm	45 mm	344 g	360	n	Feb 2014	599	ebay.com
14.		Sony NEX-3	117 mm	62 mm	33 mm	297 g	330	n	May 2010	599	ebay.com
15.		Sony NEX-3N	110 mm	62 mm	35 mm	269 g	480	n	Feb 2013	499	ebay.com
16.		Sony NEX-5N	111 mm	59 mm	38 mm	269 g	460	n	Aug 2011	699	ebay.com
17.		Sony NEX-C3	110 mm	60 mm	33 mm	225 g	400	n	Jun 2011	599	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
Convert to Imperial

The price is, of course, an important factor in any camera decision. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The A5100 was somewhat cheaper (by 8 percent) than the D3100 at launch, but both cameras fall into the same price category. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down.

Sensor comparison

The size of the imaging sensor is a crucial determinant of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its background. On the downside, larger sensors tend to be more expensive and lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature an APS-C sensor, but their sensors differ slightly in size. The sensor area in the A5100 is 3 percent bigger. They nevertheless have the same format factor of 1.5. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the A5100 offers a higher resolution than the D3100 (14.2MP), but the A5100 has smaller individual pixels (pixel pitch of 3.91μm versus 5.01μm for the D3100). Yet, the A5100 is a much more recent model (by 4 years) than the D3100, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units.

The resolution advantage of the Sony A5100 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A5100 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Nikon D3100 are 23 x 15.4 inches or 58.5 x 39 cm for good quality, 18.4 x 12.3 inches or 46.8 x 31.2 cm for very good quality, and 15.4 x 10.2 inches or 39 x 26 cm for excellent quality prints.

The A5100 has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.

The Nikon D3100 has a native sensitivity range from ISO 100 to ISO 3200, which can be extended to ISO 100-12800. The corresponding ISO settings for the Sony Alpha A5100 are ISO 100 to ISO 25600 (no boost).

Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. This service is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). Of the two cameras under consideration, the A5100 offers substantially better image quality than the D3100 (overall score 13 points higher). The advantage is based on 1.3 bits higher color depth, 1.4 EV in additional dynamic range, and 0.6 stops in additional low light sensitivity. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Nikon D3100	APS-C	14.2	4608	3072	1080/24p	22.5	11.3	919	67
2.		Sony A5100	APS-C	24.0	6000	4000	1080/60p	23.8	12.7	1347	80
3.		Nikon D40	APS-C	6.0	3008	2000	none	21.0	11.0	561	56
4.		Nikon D40X	APS-C	10.0	3872	2592	none	22.4	11.4	516	63
5.		Nikon D60	APS-C	10.0	3872	2592	none	22.5	11.4	562	65
6.		Nikon D3000	APS-C	10.0	3872	2592	none	22.3	11.1	563	62
7.		Nikon D3200	APS-C	24.1	6016	4000	1080/30p	24.1	13.2	1131	81
8.		Nikon D5000	APS-C	12.2	4288	2848	720/24p	22.7	12.5	868	72
9.		Nikon D5100	APS-C	16.1	4928	3264	1080/30p	23.5	13.6	1183	80
10.		Nikon D7000	APS-C	16.1	4928	3264	1080/24p	23.5	13.9	1167	80
11.		Sony A3000	APS-C	19.8	5456	3632	1080/60i	23.7	12.8	1068	78
12.		Sony A5000	APS-C	19.8	5456	3632	1080/60i	23.8	13.0	1089	79
13.		Sony A6000	APS-C	24.0	6000	4000	1080/60p	24.1	13.1	1347	82
14.		Sony NEX-3	APS-C	14.0	4592	3056	720/30p	22.1	12.0	830	68
15.		Sony NEX-3N	APS-C	16.0	4912	3264	1080/60i	22.8	12.5	1067	74
16.		Sony NEX-5N	APS-C	16.0	4912	3264	1080/60i	23.6	12.7	1079	77
17.		Sony NEX-C3	APS-C	16.0	4912	3264	720/30p	22.7	12.2	1083	73

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the A5100 provides a faster frame rate than the D3100. It can shoot movie footage at 1080/60p, while the Nikon is limited to 1080/24p.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the D3100 has an optical viewfinder, which can be very useful when shooting in bright sunlight. In contrast, the A5100 relies on live view and the rear LCD for framing. The adjacent table lists some of the other core features of the Nikon D3100 and Sony A5100 along with similar information for a selection of comparators.

Core Features

		Camera Model	Viewfinder (Type or 000 dots)	Control Panel (yes/no)	LCD Specifications (inch/000 dots)	LCD Attach- ment	Touch Screen (yes/no)	Max Shutter Speed *	Max Shutter Flaps *	Built-in Flash (yes/no)	Built-in Image Stab
1.		Nikon D3100	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
2.		Sony A5100	none	n	3.0 / 922	tilting	Y	1/4000s	6.0/s	Y	n
3.		Nikon D40	optical	n	2.5 / 230	fixed	n	1/4000s	2.5/s	Y	n
4.		Nikon D40X	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
5.		Nikon D60	optical	n	2.5 / 230	fixed	n	1/4000s	3.0/s	Y	n
6.		Nikon D3000	optical	n	3.0 / 230	fixed	n	1/4000s	3.0/s	Y	n
7.		Nikon D3200	optical	n	3.0 / 921	fixed	n	1/4000s	4.0/s	Y	n
8.		Nikon D5000	optical	n	2.7 / 230	full-flex	n	1/4000s	4.0/s	Y	n
9.		Nikon D5100	optical	n	3.0 / 921	swivel	n	1/4000s	4.0/s	Y	n
10.		Nikon D7000	optical	Y	3.0 / 921	fixed	n	1/8000s	6.0/s	Y	n
11.		Sony A3000	202	n	3.0 / 230	fixed	n	1/4000s	2.5/s	Y	n
12.		Sony A5000	none	n	3.0 / 461	tilting	n	1/4000s	3.5/s	Y	n
13.		Sony A6000	1440	n	3.0 / 922	tilting	n	1/4000s	11.0/s	Y	n
14.		Sony NEX-3	optional	n	3.0 / 920	tilting	n	1/4000s	7.0/s	n	n
15.		Sony NEX-3N	optional	n	3.0 / 460	tilting	n	1/4000s	4.0/s	Y	n
16.		Sony NEX-5N	optional	n	3.0 / 920	tilting	Y	1/4000s	10.0/s	n	n
17.		Sony NEX-C3	optional	n	3.0 / 920	tilting	n	1/4000s	5.5/s	n	n
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One differentiating feature between the two cameras concerns the touch sensitivity of the rear screen. The A5100 has a touchscreen, while the D3100 has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.

The D3100 writes its imaging data to SDXC cards, while the A5100 uses SDXC or Memory Stick PRO Duo cards. The A5100 supports UHS-I cards (Ultra High Speed data transfer of up to 104 MB/s), while the D3100 cannot take advantage of Ultra High Speed SD cards.

Connectivity comparison

For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Nikon D3100 and Sony Alpha A5100 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

Input-Output Connections

		Camera Model	Hotshoe Port	Internal Mic / Speaker	Microphone Port	Headphone Port	HDMI Port	USB Port	WiFi Support	NFC Support	Bluetooth Support
1.		Nikon D3100	Y	mono / mono	-	-	mini	2.0	-	-	-
2.		Sony A5100	-	stereo / mono	-	-	micro	2.0	Y	Y	-
3.		Nikon D40	Y	- / -	-	-	-	2.0	-	-	-
4.		Nikon D40X	Y	- / -	-	-	-	2.0	-	-	-
5.		Nikon D60	Y	- / -	-	-	-	2.0	-	-	-
6.		Nikon D3000	Y	- / -	-	-	-	2.0	-	-	-
7.		Nikon D3200	Y	mono / mono	Y	-	mini	2.0	-	-	-
8.		Nikon D5000	Y	mono / mono	-	-	mini	2.0	-	-	-
9.		Nikon D5100	Y	mono / mono	Y	-	mini	2.0	-	-	-
10.		Nikon D7000	Y	mono / mono	Y	-	mini	2.0	-	-	-
11.		Sony A3000	Y	stereo / mono	-	-	mini	2.0	-	-	-
12.		Sony A5000	-	stereo / mono	-	-	micro	2.0	Y	Y	-
13.		Sony A6000	Y	stereo / mono	-	-	micro	2.0	Y	Y	-
14.		Sony NEX-3	Y	stereo / mono	-	-	mini	2.0	-	-	-
15.		Sony NEX-3N	-	stereo / mono	-	-	micro	2.0	-	-	-
16.		Sony NEX-5N	Y	stereo / mono	-	-	mini	2.0	-	-	-
17.		Sony NEX-C3	Y	stereo / mono	-	-	mini	2.0	-	-	-

It is notable that the D3100 has a hotshoe, while the A5100 does not. This socket makes it possible to easily attach optional accessories, such as an external flash gun.

Both the D3100 and the A5100 have been discontinued, but can regularly be found used on ebay. The D3100 was replaced by the Nikon D3200, while the A5100 does not have a direct successor. Further information on the features and operation of the D3100 and A5100 can be found, respectively, in the Nikon D3100 Manual (free pdf) or the online Sony A5100 Manual.

Review summary

So what conclusions can be drawn? Is there a clear favorite between the Nikon D3100 and the Sony A5100? Which camera is better? A synthesis of the relative strong points of each of the models is listed below.

Arguments in favor of the Nikon D3100:

• Easier framing: Has an optical viewfinder for image composition and settings control.
• Longer lasting: Can take more shots (550 versus 400) on a single battery charge.
• Better lighting: Features a hotshoe and can thus hold and trigger an external flash gun.
• More heavily discounted: Has been available for much longer (launched in August 2010).

Advantages of the Sony Alpha A5100:

• More detail: Has more megapixels (24 vs 14.2MP), which boosts linear resolution by 30%.
• Better image quality: Scores substantially higher (13 points) in the DXO overall evaluation.
• Richer colors: Generates noticeably more natural colors (1.3 bits more color depth).
• More dynamic range: Captures a broader range of light and dark details (1.4 EV of extra DR).
• Better low-light sensitivity: Can shoot in dim conditions (0.6 stops ISO advantage).
• Better video: Provides higher movie framerates (1080/60p versus 1080/24p).
• Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
• More detailed LCD: Has a higher resolution rear screen (922k vs 230k dots).
• More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
• Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
• More selfie-friendly: Has an articulated screen that can be turned to be front-facing.
• Faster burst: Shoots at higher frequency (6 vs 3 flaps/sec) to capture the decisive moment.
• More compact: Is smaller (110x63mm vs 124x96mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 222g or 44 percent) and is thus easier to take along.
• Easier travel charging: Can be conveniently charged via its USB port.
• More legacy lens friendly: Can use many non-native lenses via adapters.
• Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
• Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
• Faster buffer clearing: Has an SD card interface that supports the UHS-I standard.
• More modern: Reflects 4 years of technical progress since the D3100 launch.

If the count of individual advantages (bullet points above) is taken as a guide, the A5100 is the clear winner of the contest (20 : 4 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro shooter. Hence, the decision which camera is best and worth buying is often a very personal one.

How about other alternatives? Do the specifications of the Nikon D3100 and the Sony A5100 place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings whether the two cameras rank among the cream of the crop.

In any case, while the comparison of technical specifications can provide a useful overview of the capabilities of different cameras, it remains incomplete and does no justice, for example, to the way the D3100 or the A5100 perform in practice. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable.

Expert reviews

This is why hands-on reviews by experts are important. The table below provides a synthesis of the camera assessments of some of the best known photo-gear review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.

Expert Camera Reviews

		Camera   Model	AP   score	CL   score	DCW   score	DPR   score	EPZ   score	PB   score	Camera Launch	Launch Price (USD)	Street Price
1.		Nikon D3100	5/5	+ +	..	72/100	4.5/5	4.5/5	Aug 2010	599	ebay.com
2.		Sony A5100	4.5/5	+	..	..	4.5/5	5/5	Aug 2014	549	ebay.com
3.		Nikon D40	..	81/100	..	+ +	o	4.5/5	Nov 2006	499	ebay.com
4.		Nikon D40X	..	79/100	..	+ +	4/5	4/5	Mar 2007	729	ebay.com
5.		Nikon D60	..	80/100	..	+ +	4/5	4.5/5	Jan 2008	629	ebay.com
6.		Nikon D3000	..	+	..	72/100	4/5	4.5/5	Jul 2009	599	ebay.com
7.		Nikon D3200	5/5	+ +	..	73/100	4.5/5	4.5/5	Apr 2012	599	ebay.com
8.		Nikon D5000	..	+ +	..	75/100	4/5	4.5/5	Apr 2009	749	ebay.com
9.		Nikon D5100	5/5	+ +	..	76/100	4.5/5	4.5/5	Apr 2011	749	ebay.com
10.		Nikon D7000	4/5	..	..	80/100	4.5/5	4.5/5	Sep 2010	1,499	ebay.com
11.		Sony A3000	3/5	+	..	..	4/5	4/5	Aug 2013	329	ebay.com
12.		Sony A5000	3/5	+	..	..	4.5/5	4.5/5	Jan 2014	449	ebay.com
13.		Sony A6000	5/5	+	4.5/5	80/100	4.5/5	5/5	Feb 2014	599	ebay.com
14.		Sony NEX-3	..	..	..	70/100	4.5/5	4/5	May 2010	599	ebay.com
15.		Sony NEX-3N	3/5	..	..	..	4.5/5	4.5/5	Feb 2013	499	ebay.com
16.		Sony NEX-5N	3/5	+ +	..	79/100	4.5/5	4.5/5	Aug 2011	699	ebay.com
17.		Sony NEX-C3	3/5	+ +	..	74/100	4.5/5	4/5	Jun 2011	599	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

The above review scores should be interpreted with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. Hence, a score should always be seen in the context of the camera's market launch date and its price, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

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Other camera comparisons

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just use the search menu below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.

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